Patent GB-295421-A (GB)
Title: Improvements in telephone systems
IPC: H04M3/14
Filed: 1927-05-10
Abstract: 295,421. Standard Telephones &. Cables, Ltd., Wright, E. P. G., Baker, J. H. E., and Cameron, A. H. May 10, 1927. Automatic exchange systems. - In a system employing conversational switches of the singlemotion step-by-step type, these switches at all stages subsequent to the first selector are controlled by marking switches which are set by impulses sent out from a code-translating registercontroller. All the component switches of the register-controller are also of the singlemotion step-by-step type and the code-translating switches are controlled in the selection of a particular group of contacts by marking switches. Instead of the usual hunting switch by means of which an idle register-controller is seized, the register-controller is permanently associated in multiple with each of a group of first selectors and is operatively associated with any one of them by the operation of a relay in the selector when the latter is seized. The marking switches are similarly multipled in common to a number of group or final selectors. The setting of the first selector is controlled by direct marking from the register-controller, this marking being effected by the sending switch which at this stage sends no impulses but subsequently transmits impulses to the various marking switches. In the system described with reference to the drawings which should be arranged as shown in Fig. 5 (Comp.), a link circuit LC, Fig. 1 (Prov.), is seized by the allotting switch a - - f when a call is initiated and causes a hunting switch GF to select an idle first selector, Fig. 2 (Prov.), associated with an idle registercontroller, Figs. 1-4 (Comp.), after which the finder LF hunts for the calling line. The call is subsequently extended over a second selector, Fig. 9 (Prov.); a relay group, Fig. 10 (Prov.), associated with the outgoing end of an interexchange junction; an incoming or tandem selector, Fig. 11 (Prov.); and a final selector, Fig. 12 (Prov.). For calls to private branch exchanges, the final selector, Fig. 13 (Prov.), should replace that in Fig. 12. In each of the Figs. 9-13, the apparatus below the horizontal dotted line including control relays and marking switches is multipled in common to a number of selectors or junctions. Fig. 14 (Prov.) shows a routine testing equipment for testing in turn each of a number of marking-switch equipments such as that shown in Fig. 9 (Prov.). The registercontroller comprises two code-translating switches AC, B, each of single-motion type, the switch AC being first set to a group of contacts marked by the register ADM in accordance with the first code digit and subsequently moved directly by the third code digit to a contact within the group, whilst the switch B is first set to a group marked by the second code-digit register BUM and may subsequently be set under control of a jumper from a bank of AC to a contact within the group. The groups of B may be unequal in size. Either of the switches may be employed for controlling the translated digits. If more than the normal number of routing digits is required the switch B is advanced one step and the extra digits are determined by the same wipers of B as were used for the other digits. The digit-skipping arrangements are such that a jumper to a special skip terminal is not required when the normal number of routing digits is employed although this number is less than the maximum provided for. Fig. 15 (Prov.) shows an arrangement for automatically indicating on an indicator the number of a calling line on which a permanent loop exists. The Provisional Specification describes a register-controller which differs in a few minor respects from that described below. A number of the features described in the present Specification form the subjectmatter of divided applications 295,445, 295,446, 295,447, 295,448, 295,449, 295,550, and 295,551. Non-numerical switching. Fig. 1 (Prov.). Line relay L energizes relay 2 which causes magnet RD to advance the allotter a - - f in search of an idle link circuit LC having access to an idle group selector associated with an idle registercontroller. When such is found, relay 1 operates over wiper b, shunts its lower winding to mark the link circuit busy to other allotters, and connects up relay 4 which re-energizes magnet RD without, however, moving the wipers of the allotter. Relay 4 also causes magnet RS to advance the hunting switch GF in search of an idle group selector associated with an idle register-controller and when such is found relay 3 operates over wiper f and the test wiper of switch GF and connects up magnet RF which rotates the finder LF. When the calling line is reached, relay 5 operates over wipers d, T, and energizes relay 6 which releases 5 and connects relays A, K in series both of which operate so that the connection is extended to the line relay L1 of the group selector. Relay 6 also releases relays 2, 4, 3 and the allotter wipers are advanced one step. Seizure and setting of register-controller. Figs. 1-4 (Comp.); absorbing a false impulse. Line relay L1 energizes relay B which completes a circuit for relay K1 in series with relay 51 in the register-controller. Relay B at its contact 3, marks the selector busy and at its contact 4 opens a circuit which in combination with similar circuits in the other selectors associated with a particular link LC marks the link non-selectable when it has access to no idle selector associated with an idle register-controller. Relay K1 connects the selector to the register-controller whilst relay S1 marks busy all other selectors associated with the same register-controller. Relay 51 also starts up the motor MD for driving the impulse springe, energizes relay 31, and connects springs LS to relay LG which after the springs have closed and opened operates fully and connects springs MS to relay CC. The complete operation of CC closes a circuit for the magnet SCM of the sender control switch which moves into position 2 and releases CC. (If the springs are faulty, switch SC will not step from position 1 and relay 21 will operate after the receipt of the first digit over contacts 9(61), SC2, 10(61), BU4, DD3, 4(51). Relay 21 energizes relay N, Fig. 2 (Prov.), which releases relay k1 and the registercontroller and connects up a special tone NU). The impulses of the, first digit are repeated by relay L1 over relay 9 and wiper DD1 to magnet ADM. If a single false impulse is sent, a restoring circuit is completed for magnet ADM over wiper C4 in position 2 of wiper AD2 as soon as relay 9 releases. If the digit is greater than 1, however, a circuit is completed over wipers DD4, AD4, C3 for magnet CM which advances register C one step so that magnet ACM is operated over contacts 1 (7), 3 (61), C4, 6 (51). Switch AC is rotated until wiper AC5 reaches a contact jumpered to the selected contact in the bank of AD4 when relay 7 operates. Magnet DDM is energized over contacts 1(9), DD2, 7(LC), C4, so that at the end of the digit the release of relay 9 advances DD one step and the second digit passes to magnet BUM. When register BU moves to position 2 magnet BM is energized over contacts 1(8), 6(61), BU3, DD3, and switch B is rotated until wiper B5 reaches a contact jumpered to the selected contact in bank BU4 when relay 8 operates. The third digit passes directly to magnet ACM which advances its wipers over the group to which they were previously set, and the four numerical digits are recorded on registers M, C, AD, BU, respectively, restoring circuits for C and AD having been completed after the third digit and for BU after the fifth digit so that these registers are used a second time. Translating-switch arrangements. The transmission of the translated digits may be controlled over the wiper of either switch AC or switch B. Switch AC has 100 terminals each of which corresponds to a particular combination of first and third digits and is used for codes having such digits and a particular second digit. For further codes having the same first and third digits but different second digits the switch B is used. When switch AC is to be used, the appropriate contact in the bank AC5 is jumpered to a contact in the appropriate group of bank B5. When switch DD moves to position 4, relays 7, 8, release and relay 61 operates and completes a circuit over contacts 1 (8), 6 (61), B1, 6 (51), for magnet BM which rotates switch B. Relay 7 energizes over wipers AC5, B5, when the jumpered terminal is reached, but the switch continues to rotate until its normal position is reached. A circuit is then completed over wipers B1, SC3 and springs MS for relay CC. When switch B is used for translation the corresponding contact in the bank of AC6 is jumpered to B5. Switch B rotates as before but is stopped when the jumpered contact is reached by the operation of relay 8, this relay at the same time completing a restoring circuit for AC over wiper AC1 which when the normal position is reached completes the circuit of relay CC. Translation is effected over a common distributing frame comprising a series of resistances Y - - X with intermediate points 1 - - 0 which are jumpered to the banks AC2 - - AC4, B2 - - B4. The arrangements for dealing with different numbers of routing digits are referred to in a later paragraph. Control of first selector. The operation of relay CC connects springs MS over contacts 7(61), B1(assuming that switch AC is being used), 6(51) to magnet SSM which advances the sending switch SS. Prior to the operation of CC, a circuit was completed from earth over wiper SS6, contacts 2(61), 4(M1), relay I, contacts 4(CC) and resistance R to battery, and when CC pulled up relay I remained operated from earth at Y over front contacts 4(CC), relay ZS, wipers SC4, B2; jumper to point 5 (assuming value of first translated digit to be 5), to battery at X. Relay I is of high resistance and serves to prevent a virtual short-circuiting of part of the